Unit 7Chapter 23Plant Structure and Function

Typical plant cell

Plant Tissues

1) Dermal Tissue For covering and

protection, and controlling water loss

Examples: epidermis, including cuticle of leaves, guard cells & stomata

Plant Tissues 2) Vascular tissue For transport of

food, minerals and water

Examples: Xylem (for

transporting upward from roots)

Phloem (for transporting downward from leaves)

Phloem

Xylem

Plant Tissues

3) Ground tissue For storage, food

production, strengthening and support

Examples: cortex, pith, mesophyll

cortex

pith

Plant Tissues

4) Meristematic tissue

For production of new cells

Examples: growing tips in roots and stems (shoots)

Apical Meristem of Shoot

Roots

Types of root systems: 1) taproot

One main root with branches

Ex: carrot 2) fibrous

Many small branching roots

Ex: grass

To anchor, absorb, and conduct

Root Structure

1) Root cap Protective covering

of root tip

2) Apical Meristem Region of cell

division (where mitosis occurs)

Root Structure 3) Epidermis

May contain root hairs for increasing surface area

4) Cortex Ground tissue

for storage of food and water

cortex

Root Structure 5) Endodermis

Waterproof cells that control flow of water into vascular tissue

6) Pericycle Produces

lateral roots

Root Structure• 7) Xylem

(star-shaped center)

Transports water upward

• 8) Phloem (between rays of star)

Transport food downward

Stems To support, conduct,

and store

Arrangement of Vascular Bundles:

Monocots Randomly scattered

Dicots Radially arranged

Can you classify these stems?

Woody stems Bark

Composed of cork, phloem, & vascular cambium

Wood Composed entirely

of xylem tissue Contains annual

growth rings Pith (young stems)

Pith

Pith

Translocation The movement of sugars through the phloem,

from the source (origin) to the sink (storage area, such as root or fruit)

Leaves For photosynthesis and transpiration

1) Blade (flat green portion)

Simple One undivided blade

Compound Blade divided into leaflets

2) Petiole (stalk) Contains vascular tissue, attaches to stem

Leaf structure 3) Epidermis

Upper epidermis produces waxy cuticle to prevent water loss

Lower epidermis contains guard cells & stomata to control water loss

cuticle

Leaf structure 4) Mesophyll

Photosynthetic tissue made up of palisade & spongy cells

5) Veins Contains xylem &

phloem cells

Transpiration Evaporation of water through stomata

Plants lose 90% of the water they transport from the roots by transpiration. What happens to the other 10%?

When water enters the guard cells, pressure causes them to bow, opening the stoma

When water leaves the guard cells, pressure is lost and the cells come together, closing the stoma

Plant hormones Like animals, plants produce hormones to

regulate growth & development

Hormones are chemicals produced in one part and transported to another to effect a change

Examples of plant hormones are Auxin, Gibberellins, Cytokinins, & Ethylene

(Without) (With) Gibberellin

Tropic responses in plants Tropism is a plant’s response toward a stimulus, such as gravity (gravitropism), light (phototropism) or touch (thigmotropism)

Ex: phototropism is the growth of a plant toward light

Nastic responses in plants Nastic movements are NOT dependent on the

direction of the stimulus

For example: in a Venus’s fly-trap, the insect triggers sensitive hairs on the surface and the leaf snaps shut